For more than 20 years the research effort on controlled thermonuclear fusion has been dominated by problems associated with magnetic confinement. But, so far, all attempts to achieve useful controlled fusion energy released by these methods have been unsuccessful. Therefore, recently, there have been attempts to solve the controlled thermonuclear fusion problem by producing a microsize hydrogen bomb. To accomplish this it is necessary to replace the fissionable material (atomic bomb) which is used as a trigger by a small clean energetic trigger which is capable of producing the very high temperatures required to ignite a very small thermonuclear explosion within a small volume of dense T-D (tritium-deuterium) mixture Of course, the size of the explosion has to be limited in order to be controlled, but the energy released should be at least equal to that required to produce the trigger which may be as much as 10.sup.9 joules. Thus, the major problem in producing such a controlled microsize hydrogen explosion is to develop a trigger which is capable of dissipating a large amount of energy in a small volume of a dense T-D mixture within a very short time. This time is determined by the time required for the plasma to cool due to the mechanism with the most rapid rate of energy loss which may be different for different configurations.
An ideal trigger would then produce the necessary energy in a very short pulse which could be readily guided to the target and focused into the small volume of the target. The energy would be in a form such that it is totally absorbed by the small amount of target material preferably in a manner so that the target material is heated uniformly. Thus, because of the ease with which short pulse length, high power laser beams can be guided to targets and focused into small volumes, they have been considered as a trigger. These beams have been used to generate high temperature dense plasmas from which a few (10.sup.4) neutrons have been obtained. However, the energy limit of currently available lasers imposes severe restrictions on their use for this purpose and even though the laser beams energy is rapidly absorbed in dense T-D targets it is absorbed near the surface only (even for targets of the size of say 50 microns in diameter) and the bulk of the target must be heated either by electronic heat conduction or by compression.
Relativistic electron beams possess energies several orders of magnitude larger than the best laser beams, and they also have been considered as a trigger. But, they have not been used in the past for this purpose because of the difficulties associated with focusing and guiding them to the targets, their relatively long pulse lengths (tens of nanoseconds), and their long energy deposition lengths in dense mixtures of T-D. In some considerations for the use of electron beams, geometrical configurations are depended on for focusing the electrons and such configurations have never worked in experiments.
Therefore, it is an object of this invention to provide an electron beam of more than 10.sup.4 joules and to focus the electron beam to a relatively small diameter and accurately guide the electron beam to a small target.
Another object of this invention is to provide electron beams of more than 10.sup.6 joules and to focus these electron beams to diameters of one mm or less.
Still another object of this invention is to provide a device for producing a trigger for a "controlled" thermonuclear explosion.
Still another object of this invention is to provide a device in which a trigger is used to produce a high temperature, high density T-D plasma which is contained for times long enough for the copious production of neutrons and for the release of thermonuclear energy.
Still another object of this invention is to provide a device in which the confinement time is determined by the rate of energy lost by radiation and to provide a device in which the radiation loss is low enough to allow the use of currently produced electron beams.